THE GYMNOTID EELS OF TROPICAL AMERICA. 169 
it was free-swimming. It is probable therefore that most of the food is taken 
while it is moving. 
ELECTROPHORUS ELECTRICUS (Linnzeus). 
Snout moderate and blunt; conical teeth in both jaws; mouth large; size up 
to seven feet. 
No stomachs of this species were examined. From the references given below 
its food seems to consist for the most part of small fishes and freshwater shrimps. 
The data are for large eels only and in two or three instances show the kinds of 
food which is taken when in captivity, rather than the normal food as chosen by 
the free fish. The authority is stated and followed by the food mentioned. 
Sachs, Zitteraal, p. 108: “especially freshwater crustacea, also small fish, 
small crayfish, many insects, and grasshoppers.”’ 
Flagg, Trans. Am. Philos. Soc., Vol. ii, p. 172: “Its common food is shrimps 
or any small fish.”’ 
Garden, Trans. Am. Philos. Soc., 1775, p. 110: ‘Small fish, also any animal 
food if it is cut so they can swallow it.” 
Faraday after Humboldt, Experimental Researches, 1753, p. 3: “Boiled 
meat and bread, small fish.” 
Sachs, l. c., 110: ‘‘ Nothing dead, except dead fish.” 
STERNOPYGUS MACRURUS (Bloch and Schneider). 
Snout rather blunt; minute teeth in patches in both jaws; mouth moderately 
large; size, up to 500 mm. 
Sternopygus macrurus (Bloch and Schneider). 
The contents of twenty-nine stomachs of this species were examined. Three 
items are found distributed in the table much as in the table given for G. carapo, 
namely: fishes, malacostraca, and entomostraca. The first two were eaten only 
by the fish above 290 mm. in length, while the last named were only in the stomachs 
of specimens less than 100 mm. in length. The most noticeable difference between 
the food of G. carapo and S. macrurus is the amount of insects consumed by the 
latter. Adult insects form the major portion of the food, not only of the medium- 
sized individuals, but of the eels above 100 mm. long. Four hundred and three 
adult insects were counted, of which three hundred and twenty-one were aquatic 
Coleoptera (for the most part Gyrinide) ; seventy-five aquatic Hemiptera (Coriside 
and Notonectide) ; four terrestrial Coleoptera (Carabide); three terrestrial Hemip- 
tera (Reduviide and Pentatomide). They are all surface-forms or land-forms 
which could easily reach the water. The eighty-two insect larvee were identified 
as follows: fifty-three Diptera; one Odonate; twenty-one Trichoptera, and seven 
doubtful. Seventeen fishes (Characins), one Amphipod, three Isopods, and three 
freshwater shrimps with fourteen entomostraca made up the rest of the food. 
The main food of medium-sized specimens is adult insects. In two larger indi- 
